This invention relates to an improvement in apparatus for making continuous metal filaments, particularly amorphous metal filaments, by depositing molten metal onto the peripheral surface of a rotating annular chill roll to form a solid filament thereon. By means of this improvement, contact between the peripheral surface of the chill roll and the solidified filament is prolonged, the point of stripping of the solid filament from the chill roll is controlled, and conveyance of the stripped filament to a suitable collection point such as an automatic winding mechanism is aided.
For purposes of the present invention, a filament is a slender body whose transverse dimensions are much less than its length. In that context, filaments may be bodies such as ribbons, sheets or wires, of regular or irregular cross-section.
It is already known to make metal filaments by directing a jet of molten metal against a moving quenching surface whereon it is solidified. One of these known methods involves chill roll casting wherein a free jet of molten metal is impinged upon the peripheral surface of a rotating drum whereon it is solidified to form a filament which is then flung away from the drum by centrifugal action. Chill roll casting techniques employing the peripheral surface of a rotating drum or cylinder have, for example, been described by Strange and Pim in U.S. Pat. No. 905,758. The procedure described by Strange et al. may be readily employed to form filaments of many of the polycrystalline metals which possess sharp melting points, that is to say which have solid-liquid transition range of less than about 5.degree. C. However, amorphous or glassy metals often have a transition range in the order of about 400.degree. C. or more through which the viscosity of the metal gradually increases until the critical glass transition temperature is reached and it is necessary for the filament to be quenched below its glass transition temperature before departure from the quench roll. This is difficult to achieve by the procedure of Strange et al. because centrifugal force tends prematurely to fling the filament away from the drum surface. Also, by the procedure of Strange et al., the point at which stripping of the filament from the surface of the drum occurs varies, so that it is difficult to collect the filament and to guide it to a suitable winder.
Shortcomings concerning retention time of filament on the surface of the drum, and difficulties in collecting the filament from a variable point of stripping are overcome by the procedure described by Kavesh in U.S. Pat. No. 3,856,074, involving recovery of filaments formed on the exterior surface of a rotating drum by using nipping means.
It is an object of the present invention to provide a further apparatus for obtaining controlled retention of metal filament formed on the peripheral surface of a rotating chill roll.
It is another object of the present invention to provide apparatus for controlled retention of filament formed on the peripheral surface of a rotating chill roll which also permits stripping of the filament at a predetermined point, and which provides means for conveying the stripped filament to a suitable collection place, such as an automatic winder.